The Cold War was a term describing a situation where two or more sides are involved in serious conflict, but don't resolve it by actual war.
Originally, it was used to describe a confrontation on Earth in the 20th century between the United States of America and the Soviet Union. However hostility between these two superpowers never escalated to a real war and was thus characterized primarily by a massive nuclear arms race and the looming threat of "Mutually Assured Destruction" (M.A.D.), that in the event of a nuclear strike both nations would inevitably empty their entire arsenal to ensure the total annihilation of the other. The term was also used to describe similar political situation on alien planets such as the Kelowna-Tirania-Andari Federation confrontation on Langara and the Rand-Caledonian conflict (which eventually ended up actual war) on Tegalus. (SG1: "Shadow Play", "Homecoming", "Icon", "Ethon")